【Abstralt】Objective To evaluate the effect of high volume hemodiafiltration (HDF) and tolerance of patients to the treament.Methods 32 of maintenance hemodialysis patients who associated with hypertension, hypotension, arrhythmia, angina pectoris, uremicpr uritus and severe calcium-phosphate metabolic disorder during HD were randomly divided into two groups. The patients received high volume post-dlilution HDF(substitute fluid 20L) and high-flux hemodialysis respectively. F60 dialysers were employed for all groups.Results The group of high volume HDF showed better tolerance than the group of HD, the dialysis complications were much less in high volume HDF patients than that of HD (P<0.01). The clearances fo β2-MG, BUN, Scr and SP were higher than that of HD. Conclusion High volume HDF is an effective method for removing low and middle molecular uremic toxins. It improves patient's tolorance to dialysis treatment and decreases the episode of hypertension, hypotension, arrhythmia and angina.